Human breast cancer is a multifactorial, multistep disease wherein genetic, endocrine and dietary factors represent crucial regulators of initiation, promotion and progression. Preclinical investigations utilizing human breast carcinoma derived cell lines either in culture, or upon xenotransplantation, have provided valuable leads for molecular pathogenesis of cancer progression and also for novel therapeutic modalities. The mechanistic significance of genetic factors on early events of initiation/promotion, however, is dependent on extrapolation, and is therefore, equivocal. Human tissue derived explant culture/cell culture models utilizing non-involved target tissue at risk for carcinogenic transformation provide a novel approach that minimizes extrapolation for clinical relevance and thereby maximizes the translational impact. This report provides an overview of laboratory investigations focused on: i) development of the model, ii) optimization of mechanistic biomarker assays for carcinogenic transformation, and iii) validation of the model as a high throughput mechanistic screen for preclinical efficacy of natural phytochemicals.